Field of the Invention
The present invention relates to an antenna module, and more particularly, to an antenna module applicable to an Industry-Science-Medical (ISM) band.
Discussion of Related Art
An Industry-Science-Medical (ISM) band is a frequency band designated for radio frequency energy use in industrial, scientific, and medical fields rather than telecommunications. According to the trends of miniaturization and lightening of electronic devices, an antenna module embedded in an electronic device using the ISM band needs to be designed to a small-size.
FIG. 1 illustrates an example of a Meander type Planar inverted-F Antenna (PIFA) antenna for the ISM band, and FIG. 2 is an example of a Monopole type antenna for the ISM band. The size of the Meander type antenna is about 27 mm by 17 mm, and the size of the monopole type antenna is about 26 mm by 19 mm. Since both the two cases illustrated require a wiring space for an antenna length corresponding to a wavelength of λ/4 to secure a resonant frequency required for 2.4 GHz of the ISM band, there is a limit in reducing the size of the antenna.
In addition, in the case of a Bluetooth Low Energy (BLE) antenna for the ISM band, the size may be reduced down to 20 mm by 11 mm through a design which utilizes a bottom surface to secure a required length of the antenna, but a problem occurs in which a frequency deviation is influenced by permittivity.